Op los angeles



Der; 1.7, 1929. A, Q RUBEL 1,740,039?? SOAKING METHOD FOR INITIATING GASLIFT IN OIL WELLS Filed Juiy 18, 1927 A TTU/e NE Y Patented Dec. 17,1929 7 -uNlri-:D` STATES ALBERT c, nennt, ormone Jemen, camroma,Assieuoa To UNION orL comm PATENT 'ori-ICE F GALIFOBNIA, OF LOS ANGELES,CALIFORNIA, A CORPORATION OF CALIFORNIA SOAKING' HETHOD FORINITIATINGAGAS LIIIT IN OIL WELLS appueauen mea my 1s, i927. serial No.zoaese.

This invention relates to the so-called gas lift method of Aflowingdeep` Wells-,particularly oil wells, and has been designed to 0vercomethe excess hydrostatic head of oil which ordinarily accumulates in suchwells prior to starting gas lift and which ordinarily cannot be -removedby'.direct vapplication of a reasonable gas pressure in attempting toinitiate gas lift. Gas lift, as now commonly practiced, consistsinpassing gas under pressure into a well containing a iiow tube, so thatthe gas passes around the lower end of the ow tube in astream 'and inits passage atomizes the oil' as fast as it is forced up to said tubeend -by the natural roclpressure ily the well, the

atomized oil being carried -to thesurface in the gas stream. The gas maybe introduced i either through the flow tube or through the hasaccumulated in the well hole, which head the flow tube head. Thus, uponany attempt to .startgas 'usuallyzcannot be overcome by steadyapplication of a moderate pressureto one side of rea-son that, aspressure is applied to one side of the tube to depress the oil levelvtherein, the

Ahydrostatic head increases inthe other side.

laVhil some of the oil is forced back into the formation (depending uponthe viscosity of the oil, the frictiouof the formation, andthe like) theeffective rock pressure in the vicinity of the well increases unt-il itis suic-ient to balance the increased hydrostatic lift by straightapplication of pressure to one side in order to force over the entireeX- cess load of accumulated oil and uncover the lower end of the tubefor passage of gas thereunder, the hydrostatic head will increase untilit reaches the maximum, that is,

until it is equal to the entire height of the iow tube, vwhich heightmay be as much as seV- This condition arises for the eral thousand feet.Moreover, the pressurek l which would be high enough to start gas` liftby suchsteady application, that is, a normal starting pressure, underthese conditions, wouldbe excessive for vall other purposes,

.since when the oil level is lowered and gas lift started, normalcontinuation of gas lift mayl be and should be carried on with a muchlower pressure, this being made possible by the much lower density 4ofthe'gas-andfoil Volume in. the flowl tube during normal as lift ascompared with the oil before gas lift.

Thus, it is clear that it is not convenient or desirable tomaintainsaidexcessive pressure merelyf'for the purpose of overcomingsaid hydrostatic head.

The term hydrostatic head except where otherwise defined, is usedthroughout this case to mean the pressure of that'portion of the oilbody accumulated in the well hole, which stands as a' column in the'tube and casing above the lower end of theflow tube.

(a fewhours or a'few days according to the well), the head will havereached Vsubstntially its maximum height and will be in substantialequilibrium with the rock pres-` vWhen a well has `stood/idle for ashort time Obviously, then, in a non-flowing well under these conditionsthe said rock pressure or hydrostatic head is less than the static headrepresentedby the length o`f the flow tube between its points ofintake'and discharge.

IfV gas under pressure be applied to the casing for example, of awellcontaining an `accumulated head lofv oil, oil will be forced up into thetube, thereby increasing thestatic head therein, as 'above indicated.'Of course,

if 'the oil level stands suflic-ientlyhigh in, the

well, the available gas pressuremay elevate the oil in the tubingsuliciently to discharge some oil fromthe tubing without uncovering 'thelower end thereof, but discharge will cease as soon as the oillevelbecomes depressed to such `a point that the head in'the If a tubingabove the oil level balances the gas .pressure being applied. i

In order to initiate gas lift by straight application of pressure, astarting pressure must be employed suiiicient to depress the oil levellow enough to, allow the pas! developed in 'the' iow tube. Thisincreased head of oil inthe tubing is here termed the normal startingliead,'and its magnitude is dependent upon .the relative size of thetubing and casing, the amount and density and viscosity of the oil invthe well, the rock pressure, the friction of the formation, etc.v Thenormal starting head as the term is herein employed is defined as thehydrostatic head of oil in the flow tube above the point of admission tosaid liow tube at the time gas would break into the flow tube. In likemanner, the normal starting pressure isv defined as the gaspressurevnecessary to depress the oil level in the gas admission tube tothe point of gas admission tothe How tube and sufficient to ,start gaslift in the flow tube .whensaid' that they definition applies whetherdis! charge flow is from the tube and gas application is through thecasing, or vice-versa. as tube is employed and is connected by a Jet totheflow tube in a manner common to air or gas lift, the starting head orpressure may be equal to thehydrostatic head of the oil in the-flow tubeabove the jet when gas is rst forced into the gas tube, and it may beequal to or slightly greater than the hydrostatic head of oil above thejet when first applied.

The general object of the present invention, is to overcome thehydrostatic head 1 and depress the oil level approximately to the lowerend ofthe flow tube by the application of gas under a pressure less thanthat required to initiate gas lift by steady application to either thetube or the casing in the usual manner, and less than the hydrostatichead naturally existing in the well prior to gas lift initiation.

The obJect is attained by promoting the absorption of a large amountofgas (natural gas preferred) by the oil body, coupled with a depressionof the oil level'to as lowA a point as possible with the availablepressure, whereby the absorbed gas materially reduces the specificgravity of at least the upper portion of the oil body and whereby theavailable pressure then becomes suiiicient to elevate and discharge thecolumn of the so-lightened oil in conjunction with the expansive andlifting properties of the absorbed gas.

g In many cases where the available pressure is not sufcient to overcomethe hydrostatic head and establishgas lift by employing .other measuresin the ordinary fashion, I have found that by continuing theapplicationof the maximum available prebsure for aprolonged period of time, iteften possible to produce a considerable depression of the oil leveltogether with such a high absorption ofgas that gas lift will commenceimmediately upon the release of pressure in the ow tube. Forconvenience, this method is termed the soak' ing method, and, brieflystated, the novelty therein resides primarily in applying to /thesurface of abody of oil collected in the well a soluble gas under apressure'less than .rock pressure and less than the normal startingpressure, maintaining said pressure for a relatively great length-oftime to cause absorption of large amounts of gas, and thenv releasingthe pressure on one side of the flow tube while continuing it on theother to initiate gas lift. Thus, a large quantity of gas is caused tobegradually absorbed bythe oil, this absorption being desired both forthe'purpose of lightening the oil body (that is, reducing its specificgravity) and for the expansive and lifting properties Vof the absorbedgas at higher levels as the oil approaches the top of the Well duringexpulsion, the expansive eEects increasing due to static'pressuredecrease as the topis approached. This step also results in graduallyforcing a considerable quantity of the accumulated oil body back intothe formation. sure is applied both to the tubing Aand the casing, andbecomesapproximately if ,not entirely equaliZed therein. After thissoaking, or maintained application of gas under pressure, has beencontinued forwhat is deemed to be a sucient length of time, the pressureon the tube (or the casing, if desired) is suddenly released whilepressureI to a natural lsurge of oil into thewell un' der pressurenaturally occurring in the formation may be employed to augment the gaspressure, the pressure on the tube being relieved at a time when a headdevelops Preferably, the presas determined by watching the pressure ygauge. Many variations of the invention are possible as will be apparentto thoseskilled in the art, a preferred embodiment being thatgenerically described above.

In the accompanying drawings the various steps are diagrammatiCaIlyrepresented for the purpose -of illustration, and in these,

Fig. 1 indicates the original condition of the well at the time gas'liftis-to be initiated;

4: fapplied .both to the .casingl and to the flow containing .Fig. 2.indicates the first stepwhereingas under the maximum available pressure/1s upon the application .of said7 l 41,740,1 iag1I F1gLv-3represeutstheeonditions attendingl will suilicient to force over theyheadof oil etube, and `to cause such absorption jij.

'f' for' a' relativelylong lperiod of time. if gas pre's'slire toinitiate gas would be maintained for' per-v haps an liour, it wouldfbenecessary ac tehiclr causes/portions of tl" .oil=body ,/,co/rding' tothe present method to main- .f.orc,ed back into/the forma/fion; 1/U ,v'tin such pressure for perhaps six, -to 105,Fgfr-4, inicatesA the dieist ofgppesswr"tiuglitf hours, and where lsuch pressure body is forced1u'p'on establishinento-Iiorriial gas'lifta. .'fljf these drawings'theusuallxvell. casing i 'i :.410 is sloivn'as receiving aflow tube/l2which depends into the-oil body, the upper end of the `casi-ng beingprovided with a connection '13 and the tube witha connection 1li-.intowhich `gas under 'pressure may be introduced by a compressor C, or from:another Well 1 lovving gas v'under sufficiently high pressure.Tl-1ellevel of oil Vwhich has .accumulated in Y Q/ehamiefirasf/,'/tirely to establish new, the maintenance ot pressurefor six'- or.eight hours aintenancejfor. one hour would fail enstancesthirty hoursand more, \vill so thoroughlysaturate the oil'tvith gas that -in a greatmany difficult-cases', flow will commence immediately upon vrelease ofthe pressure in .the iiow. tube, and the excess headot oil will cessarythat-the gas pressure'be mainbe readily expelledfby the pressure main#tained in thecasing. When theloillevel drops tothe lower'end ofthe tubeas indicated at 20, Fig. 5, nor'mal gas lift commences, v atl Vwhichtime the pressure required to eontinueoper'ation oft-lie We-ll maybedropped the eo l down below that femployed. instarting "ly 1g;thefmaximum available pressure,

:fw-which'. however, is less than'thel static head .'35V of oilditofboththe Acasing andthe flow tube.,-

lower end of the Vtube and normalgas lift 'velv longperiod of time, "ithaving been 44.found that by suchmaintenance ofpressure, :fthe body otoil Will vgradually be forced back -'i into the sands aroundthe Wellhole, as indifcatedabythe arrows in'Figs. :Zand 3, Where- 'b v the loillevel is eventuallyfbrought down vvtothepoint indica-ted fit-18 in Eig.3.. It has -thecasing and gas littby this.

'inthe oilW-hen the oil column rises toward the top o ftheflow'tube,

the absorbed lgas 65 the-devel 1G, this-ievehreprealanced in the-tubeand cas.-v

Aof the present-.invention'redes 1n maintaining this pressure-'for arela-.

- =also `:been found thatunder -.t he'se Iconditions, 4

y a relativelygreat amount of gas is absorbed {'methodgitis necessarythat 'g'as'absorption be,`

A gavailablefgas E .pressure combined with the lifting effects producedby ftheexpansion of begirsbut does not'coritinue after release'ofpressure on the oneside, `the 'entireoperation 1n aybe repeated.'vherebyfthe"resulting Surging et'ect as tlhe oilcolurinns"inthey tubeland casing rise and -fall, further;v increases" gas absorption.vAbsorption 'v 'vill 4reach 'a polnt where a portion'of oilvill be"forcedover on release,V and ifnecess'arygfurthe rep etition will eventuallyreduce-the oilI level to the COI'llllleIlCeS;

are apparent'fromthe following: In previous 'attempts to start-certainWells, ai' pressure of; 900 pounds had Abeen required, but uponcontinuously 'maintaining a pounds for eight hours, and then releasingthe tubing,` 'the Well carne over Without difficulty# Gas liftWasthereafter'continued at a pressure of 175 poundson' the casing. l

It has been found that in` Wells which The advantages of this methodiofoperation i iol .'lpressure of 500 ,headf (which, however,' i'sj truefofmost Wells) gas pressure may-be materially aug# niented b'ywatching-thepressure gauge and relea ingv theiiow tube 12 at a time when the maximumeect of-a'headoccurs. 'In fact, by

taking advantage of this 'efect,` itf' i`s frequently possible. to startWell which could not be Started if the p 'rfes'surefvvere releasedbetween heads. Toindicatethis condition, arrows directed towardthe'wellhole are employed in lVhen normalgaslift has once been initiatedby.deprssfi on"ofthe'o`il levelitothe p oint the lovver'end o f theflowtube 12,' Will be'suicient to elevate the incoming' oil 'asapidly assupplied by the natural wellpressure. Obviously, in the' operation ofthis method, it will 20, indicated ini Figb, the floWjof-lgas under lbep'ossible to'releas'e pressure upon the casing .maintain the pressureon the `flow tube whereby the oil 'will be flowedA out through aconnection 13',- and it is intended that thi-sva-v riation `shall beconsidered 'throughout to be the same invention vas owing out through'the tube. '.Also, it mightbepossible in some in' stances to closethetlowtube and apply gas toA the casing-only, or vice versa, when thewell is lg'be'ingallowed'to soak, although the advantages of thismodicationfwill' not beso marked as when pressure is applied both'to thecasing'andto'the tube.

` From the foregoing, it will-be seen that this 15 process appears todepend upon three factors,

each of which-varies according to the conditions of the individualwell.These factors are: (a) orcin'ga part `of the oil back intoAthe sands.

(b).' l`he absorption of vrelatively large p A quantities o gas underpressure to lighten the` oil and reduce the effective head.

. (c) Heading eifects in the'well.

2 5 4 It can be seen that thefunction of the absorbed gas isconsiderable-when it is cpnsidered that approximately 160 cubic feet ofnat. ural gas will .be absorbed pervbarrel of oil when 4the gas is underpressure of five hundred 'p'o unds. The 'expansionof this amount; of

gas and oil as thewell approaches -the upper' portion of ,the tubing hasa lifting effect of' approximatelythirty atmospheres, which constitutesan enormous aid to the pressure of the' ason the casing.` 'lso, itshould be noted tha the successful accomplishment under this process',is due largely' to the factor of time.'

The above disclosures are to be considered merely-.as illustrative ofthe generic inven- 1 40 tion and ynot as limiting, s ince manyvariations may be' 'made withinfthe scope of the following claims. Iclai m:. .l 1. 1. a method for initiating gas lift in oil wellscomprising a easing element and a tubingelement dependent thereinwherein the hydrostatic head of an oil bodycollected in the well isgreater than the available gas pressure, the steps comprising applyingsaid vgas pressure' to the `oil surfaceto force as much as possible ofthe oil back into the for- .mation and maintaining the pressure of thegas onthe oil to increase absorption of the gas by the oil, saidpressure being maintained for a. vconsiderable time, land. then.releasing c5 of relatively large amounts. of gas by the oil saidpressure-for a rela` and then releasing the pressure upon one side otherside.

3. In a method according to clai'm 2 where in the relea'se 'ofpressureiis timed to take 76 place when a heading effect occurs inthewell. 4. In a method for establishing"'gas'lift'jop` erations oil wells,wherein a flow tube dependslinto a body of oil. within a well cas ing,the steps comprising pplying a soluble gas to the oil in the tube and.in the casing simultaneously under a pressure less than the hydrostatichead-in.' the tube until thepressure' is balanced on both sides of thetube, re-l leasing the pressure on one side while mainso taining itonthe other, and repeating thev operation to' cause the oil to surge forfurther charging the same with gas until a portion of oil is carriedover on theireleased side and until the oil level 'in the well has beenlowered 85 to the lower end of the tube to bare the same and normal fiowby gas lift is established.

5. Ina method forinitiating gas liftin anv oil well containing a casino'into .which a flow -tube depends and in which yoil has accumii-oo lated,the 4steps comprising applying asolul" blegas under pressure lessthansufHcient toi overcome the hydrostitic head,"said..pressure 1 beingapplied-tout least one sideof'said tube, g

maintaining 'saidpressure for a relatively -`o5 long-period of timeto-depress the oil level', releasing-the pressure on. said one.s1de and.

applying it on the'other side.

6. In'amethod for initiating Agas lift i an oil well. containing a'bodyof oil the Steps 100' which comprise applying a soluble gas to thesurface of said oil un er a pressure insufficient for normallyinitiating gas lift of oil to the.

surfaceof. the well, and continuing said ap-v if `plication for aprolonged period of time until:

conditions suitable for gas lift are developed.

- 7. In a method for initiating gas lift in any oil well containing abody of oil into which. allow tube depends the steps which compriseapplying a soluble gas to the surface of the -oil under a 'pressureinsufficient to start gas lift ofoil up and out through said tube,continuing said application for a prolonged period of time untilconditions suitable for. gas i lift have been developed,`and thenreleasing pressure on one side of said tube. 8. In a method ofinitiating gas lift in an oilwell containing a body ofoil into which aflow tube depends, the steps which comprise applying a soluble gas toone side of the tube under a pressure insufficient to cause gas liftl,up and out from the other side of said tube, maintaining said pressurefora' prolonged period of time until gas lift of oil tothe surface is'accomplishe 125 9. In'a method 'ofinitiating gas lift in an oil wellcontaining a body of oil into which alflow tube depends, the steps whichcomprise applying a soluble gas to one side ofthe tube under a pressureinsuicient to cause gas lift -130 up and out from the other side ot saidtube, maintaining said pressure. fork a prolonged period of time Whilemaintaining an approximately balanced pressure on the other side of theflow tube, and' releasing the pressure' on one side ofthe flow tubepressure on the other side Signed at Los Angeles,

0s Angeles and State of 10 11th day of July,

While maintaining to obtain gas litt.v in the county of California, thisDQ 1927. LBERT C. RUBEL.

